Reactive extraction of metals from petroleum oils containing metals by oxidizing and then using aqueous phase as extracting medium can be effective process for metal reduction from hydrocarbon oils. Various chemical reagents are generally employed in the aqueous phase to facilitate the reaction and subsequent extraction along with sufficient temperature and homogeneous or heterogeneous catalyst to speed up the reaction rates. The present invention discloses use of chemically modified alcoholic derivatives of amines and their judicious mixtures in such a type of process in presence of flow of electrons that significantly improves the removal of metals from petroleum oils.
Valorization of bottom of the barrel is a major challenge to refiners. Furthermore, there are various types of so-called “heavy crude oils” which are attracting attention of refiners due to price discounts. The heavy cracked fractions derived from these heavy crudes contain large quantities of metals, sulfur and nitrogen and have a low hydrogen to carbon ratio, which makes them difficult to process.
The various ways to handle this bottom of the barrel may be grouped in two categories: carbon rejection and hydrogen addition. The carbon rejection technologies include thermal and catalytic cracking, and extraction of usable fractions from resids by means of a solvent (deasphalting). The hydrogen addition route, though a costly affair, is employed due to better quality of end products. The hydrovisbreaking route is hindered by its low conversion levels and non-availability of cheaper and efficient hydrogen donor solvents. The residue up-gradation options however face difficulty due to high metals, particularly in catalytic processes as the metal content of the feedstocks are irreversible poison to the catalyst resulting in the permanent loss of its activity. So if these metals are removed prior to the processing step, then the life of the catalysts and also their regenerability increases. The metal removal also increases the value of coke in delayed coker unit.
Currently the fixed bed demetallation is employed in the refineries, which constitutes two or more hydrodemetallation reactors operating in batchwise swing mode. The catalyst is to be changed after its deactivation due to permanent nature of deactivation by metals. Solvent deasphalting process also reduces the metal content of the feedstocks by removing asphaltenes and concentrating the metals in the asphaltenes.
The amount of metals in crude oil varies from a few parts per million to more than 1000 ppm. The metals found are sodium, potassium, lithium, calcium, strontium, copper, silver, vanadium, manganese, tin, lead, cobalt, titanium, gold, chromium and nickel.
The analysis of the closest prior art shows that there are a plurality of prior art disclosures which can be considered to be quite close to the process for metal reduction of hydrocarbon oil as disclosed in the present invention.
U.S. Pat. No. 5,855,764 (Exxon Research Engineering Co) discloses a method of decreasing the metals content of metal containing petroleum streams by forming a mixture of the petroleum fraction containing those metals and an aqueous electrolysis medium containing electron transfer agent, and passing an electric current through the mixture or through the pretreated aqueous electrolysis medium at a voltage, sufficient to remove the metals such as Ni, V and iron (Fe) from the stream (i.e. to produce a petroleum fraction having decreased content of the metals).
U.S. Pat. No. 5,529,684 (Exxon Research Engineering Co) discloses a process for demetallation where the feed, to be demetallized can have a range of vanadium and/or nickel content.
U.S. Pat. No. 6,013,176 (Exxon Research Engineering Co) provides a method for demetallization and ultimately the demetallation (particularly of metal species typically associated with hydrocarbon species and thus hydrocarbon soluble, e.g., petroporphyrins) of the metal-containing hydrocarbonaceous petroleum stream by contacting with a base, an oxygen-containing gas and at least one phase transfer agent at an effective temperature of from 100° C. to 180° C. to produce a treated petroleum stream. The oxygen containing gas is air or an effective concentration of oxygen and air mixture to produce enhanced extractability and ultimately demetallation under process conditions.
Use of electrical energy is prevalent in the prior art. Electricity used in all prior art documents considered close to the present invention was however found to be by way of electrolysis.
However, the present invention discloses a process which is unique because though it deploys electrical energy, the electricity does not result in electrolysis of the medium. The electricity used in the present invention is for providing electrons only as a new and unconventional way which enhances the process of metal reduction. The present invention also provides the means to carry the current through reaction medium in enhanced quantities by modifying the chemicals.